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Method for selectively removing outer surface acid site of molecular sieve based catalyst

A molecular sieve and catalyst technology, applied in the field of industrial catalysis, can solve the problems of low selectivity and fast deactivation rate, and achieve the effect of improving selectivity, low cost and improving shape-selective catalytic performance

Inactive Publication Date: 2019-04-26
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The present invention aims at the current problem of low selectivity in improving the shape-selective catalytic performance of ZSM-5 molecular sieve catalysts and the rapid deactivation rate caused by acid centers on the outer surface, and provides a selectivity with simple operation, low energy consumption and low cost. A method for removing acid centers on the outer surface of a molecular sieve catalyst, which can significantly improve the shape-selective catalytic performance of the molecular sieve catalyst

Method used

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  • Method for selectively removing outer surface acid site of molecular sieve based catalyst
  • Method for selectively removing outer surface acid site of molecular sieve based catalyst
  • Method for selectively removing outer surface acid site of molecular sieve based catalyst

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Experimental program
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Effect test

Embodiment 1

[0019] No template method ZSM-5 is prepared by hydrothermal method, the method is as follows: mix sodium metaaluminate, sodium hydroxide and distilled water in a beaker, slowly add silicon source (fumed silica) under high-speed stirring, and mix to form The molar composition is 100SiO 2 -1.6Al 2 o 3 -23NaOH-3000H 2 The sol of O was aged for 12 hours and transferred to a stainless steel crystallization kettle lined with polytetrafluoroethylene. After crystallization at 170°C for 96 hours, take it out, wash it, and bake it at 550°C for 7 hours to obtain ZSM-5 by the template-free method. See the attached X-ray diffraction pattern. figure 2 , its 2,6-di-tert-butylpyridine adsorption infrared spectrum is as follows image 3 shown.

[0020] The obtained ZSM-5 molecular sieves were ion-exchanged into H-type ZSM-5, treated with nM nitric acid solution at 180°C for 24 hours, the samples were taken out, filtered and dried, then put into a muffle furnace at 550°C Roasting in the ...

Embodiment 2

[0023] Catalyst evaluation reactions all use a fixed-bed reaction device, the inner diameter of the reaction tube is 8mm, and the reaction tube adopts a three-stage temperature control mode of upper, middle and lower. Evaluation devices (such as figure 1 shown) consists of two gas circuits and a liquid circuit, the gas circuits are respectively used to feed N 2 , where N 2 The function is to purge the reaction system to remove air, check the overall air tightness, and use it as a carrier gas to bring the gasified reaction raw materials into the reaction tube. The reaction solution first enters the gasification chamber through the high-pressure constant-flow pump for gasification, and then enters the reaction tube for reaction after mixing with the carrier gas in the preheating and heat preservation zone. The gas phase product after the reaction is directly analyzed by online gas chromatography through the six-way valve. In order to maintain the gas phase state of the product...

Embodiment 3

[0031] Change reactant, catalyst evaluation method is with reference to embodiment 2, and the results are shown in Table 2:

[0032] Table 2: Alkylation performance of toluene and methanol

[0033] catalyst

[0034] Note: toluene:methanol=2:1, reaction temperature 400°C, pressure 0.1MPa, WHSV=2h -1 .

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Abstract

The invention discloses a method for selectively removing the outer surface acid site of a molecular sieve based catalyst. The method comprises the following steps: with a silicon-aluminum molecular sieve prepared by a template-free method without adding organic amine as a template as a raw material, putting the silicon-aluminum molecular sieve into a plurality of concentrations of acids for treatment at the temperature of 100 to 180 DEG C for 2 to 24 h, taking out, filtering, and roasting to obtain the molecular sieve of which outer surface acid is removed. According to the method for selectively removing the outer surface acid site of the molecular sieve based catalyst provided by the invention, the method is simple in operation, energy-saving, low in consumption and low in cost, and theshape selective catalysis performance of the molecular sieve catalyst can be improved obviously.

Description

(1) Technical field [0001] The invention belongs to the technical field of industrial catalysis and relates to a method for selectively removing acid centers on the outer surface of molecular sieve catalysts. (2) Background technology [0002] Molecular sieves have regular channels, adjustable acidity, and characteristic shape selection. Since the 1960s, they have been widely used in petrochemical product processing, such as catalytic cracking, aromatics conversion, isomerization, and shape selection. Catalytic reactions such as whole and dehydration. For example, ZSM-5 molecular sieve is widely used in the catalytic process of producing p-xylene (disproportionation of toluene, isomerization of xylene, alkylation of aromatic hydrocarbons and alcohols, etc.). However, with the development of petroleum refining and petrochemical processing industries, people put forward higher and higher requirements for the catalytic activity and selectivity of molecular sieves. There are a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/40C07C15/08C07C2/86
CPCC07C2/864B01J29/40C07C15/08Y02P20/52
Inventor 吕井辉胡华雷芮佳瑶王清涛张群峰丰枫卢春山赵佳李小年
Owner ZHEJIANG UNIV OF TECH
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